Hi everyone!

This is a short rant about taking almost a year to realise the fan on my case actually worked all this time!

I bought an aluminium case that included a fan for my fancy Raspberry Pi 4. The case had a screw to hold the case together but it was placed almost on top of the fan. All this time I thought my heatsink on the CPU was working perfectly fine because the fan never turned on. I originally set the CPU temperature to 60ºC to activate the fan under raspi-config.

It was only a warm day I figured the fan should have turned on. I came to realise it was scorching 75ºC! You can check the CPU temperature with the following command:
cat /sys/class/thermal/thermal_zone0/temp

GPU temperatures were worse with it reaching above 80ºC! They were checked with the command:
vcgencmd measure_temp

Troubleshoot time! Touching the Raspberry Pi, I could feel the heat from the Pi dissipating out to the case and creating a mini hot oven. The situation seemed dire and almost certainly disastrous. The fan wasn’t working and it seemed like it was broken or I had connected the pins into the wrong spot. I slowly unscrewed the only screw holding the case intact and suddenly I hear something whirring to life. The fan works?

Apparently the screw holding the case actually blocked the blades on the fan from spinning…

Moral of the story: Don’t tighten things up if you don’t have to!

TL;DR: Make sure the screw for your Raspberry Pi case is not blocking the fan.